This invention relates to turbine technology generally, and more specifically, to the cooling of turbine bucket platforms.
A problem common to all high technology gas turbines is bucket platform endwall distress due to high temperatures and large temperature gradients. The distress may take the form of oxidation, spallation, cracking, bowing or liberation. Proposed solutions to address the problem employ either cooling enhancements for the inner surface of the bucket platform, located radially between the bucket airfoil and the bucket shank; creating convection cooling passages within the endwall; and/or adding local film cooling. Representative examples of prior attempts to solve the problem may be found in U.S. Published Application No, 2005/0095128; and U.S. Pat. Nos. 6,309,175; 5,630,703; 5,388,962; 4,111,603; and 3,897,171.
There remains a need for providing more effective cooling arrangements for employing existing cross-shank leakage within the bucket shank cavity to cool the bucket platform.